Amblyopia can happen when one eye does not see as well as the other. Sometimes the brain starts to use the eye that sees better to do the work of both eyes. That can make the eye that is not working well even weaker. It not always clear why one eye has better vision than the other.

Eye problems that can cause this are:

  • Eyes that are not aligned
  • Vision problems that are not treated
  • Having a large difference in sight between both eyes
  • Vision problems at birth, such as a cataract or droopy eyelid

Risk Factors

This problem is often noticed during childhood. Things that may raise the risk of this problem are:

  • Being born very early or being a small baby at birth
  • One or both eyes turn outward or inward
  • Having family members who had it or other eye problems as kids
  • Having developmental disabilities



Some people may not have symptoms. Others may have:

  • Blurry vision
  • Problems telling how near or far an object is
  • Squinting
  • Shutting one eye when looking at things
  • Head tilting
  • Eyes that cross


The doctor will ask about symptoms and health history. An eye exam will be done. Vision in each eye will be tested. This is often enough to make the diagnosis.



The goal of treatment is to correct vision. Any underlying eye problems will first need to be treated, such as removing a cataract. Improving vision can be done by forcing the brain to use the weaker eye so that it gets stronger. The doctor may do this with:

  • A patch worn over the stronger eye
  • Glasses that have one lens blurred
  • Eye drops to make the stronger eye blurry

Wearing the glasses or patches as the doctor advises is key to helping vision get better.

The doctor may also want to help the eyes learn how to work together again. This may be done with special games or videos.


There are no known ways to prevent this health problem. Getting regular eye exams can help find the problem early.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.